A lavender watering interval is useful only while the conditions behind it remain similar. A change in weather, pot size, growing medium or position can make the old routine inappropriate.
Check the compost and the route for excess water to escape. A container with drainage holes can still sit inside an outer pot that collects runoff.
Look at what changed
Has the plant moved under cover? Have temperatures fallen? Was it recently transferred into a much larger pot? Record these changes before deciding the plant needs more or less water by a fixed number of days.
Do not assume a dry top surface means the whole container is dry. Check the root area, particularly in a large pot with a small plant.
A brighter position and suitable drainage support the overall growing conditions, but neither is a reason to let a plant dry indefinitely. Inspect it and respond to the compost and growth. If stems or roots appear to be deteriorating, investigate the damage rather than trying to balance it with another feed. The calendar cannot diagnose the contents of the pot.
Related reading: Potted Lavender Care: Soil, Watering and Pruning.